to write set of values to a file from python

Scott David Daniels scott.daniels at acm.org
Fri Dec 16 16:28:11 CET 2005


muttu2244 at yahoo.com wrote:
> hi
> thanks every body for the help.
> Now how can check whtr the row am reading is the last row or not??
> 
> for example: ...
> reader = csv.reader(file)
> for row in reader:
>       print row
>       HERE HOW CAN I CHECK WHTR THIS ROW IS THE LAST ONE IN THE FILE
> 
> so that if at all i dint find what am searching for i can write that
> information at the last row, after opening the file in a "append" mode.

What Steve Holden says is right.  If it turns out you need to know
ahead of time, use a lagged input to determine whether it is last:

     def lagged(source):
         '''produce element,islast for elements in source'''
         generator = iter(source)
         previous = generator.next()
         for element in generator:
             yield previous, False
         yield previous, True

     file = open ('C:\some.csv','r')
     reader = csv.reader(file)
     for row, final in lagged(reader):
         print row
         if final:
             print 'final:', row
         else:
             print 'leads:', row


--Scott David Daniels
scott.daniels at acm.org



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